1. Field of the Invention
The present invention relates to a room temperature curable organopolysiloxane composition which readily cure under the action of moisture, and to a cured product of said composition. More particularly, the invention relates to a composition which does not cause contamination on surfaces of a cured product thereof or in the surroundings when used outdoors and which permits easy removal of fungi, if any, from surfaces of the cured product.
2. Description of the Prior Art
Heretofore, so-called room temperature curable organopolysiloxane compositions are known which remain stable with a flowing property under hermetically sealed conditions but which, under the action of moisture in air, cure at room temperature to form a rubber-like elastic material. This type of compositions are in extensive use as sealing material, coating material, adhesive and the like in construction, machine and electric industries.
However, these room temperature curable organopolysiloxane compositions have the disadvantage that when used as sealing material or coating material, they are liable to cause contamination on surfaces thereof or in the surroundings, thereby damaging the appearance of a building or the like. For suppressing or inhibiting such contamination, a variety of additives have been investigated and a number of methods have been proposed. For instance, there are known a method in which a surface active agent having a polyoxyethylene group, a residue group of sorbitan, a residue group of a disaccharide, or the like is used (Refer to Japanese Pre-examination Patent Publication (KOKAI) Nos. 56-76452 and 56-76453), a method in which a surface active agent having at least one fluorine atom in its molecule is used (Refer to Japanese Pre-examination Patent Publication (KOKAI) No. 58-167647), and a method in which a surface active agent having at least one fluorine atom in its molecule and an organosilicon compound having an amino group are used together (Refer to Japanese Pre-examination Patent Publication (KOKAI) No. 61-34062). However, contamination inhibitive properties given by these methods do not last long and, therefore, produce little effect on long-term contamination.
Besides, cured elastic materials obtained from known room temperature curable organopolysiloxane compositions have the drawback as follows. Although they exhibit good appearance upon application thereof, they are susceptible to contamination by various contaminants (dirt from human bodies, detergents, foods, etc.) where they are applied in a bathroom, kitchen, toilet or the like. Where these compositions are used in highly humid environments, in particular, the appearance of the applied compositions are liable to be damaged by propagation of fungi thereon.
In view of the above, as a method for imparting a mildew-proofing property to a moisture-curing type room temperature curable organopolysiloxane composition, Japanese Pre-examination Patent Publication (KOKAI) No. 54-43260 discloses addition of a benzimidazolyl alkyl carbamate to the composition, whereas Japanese Pre-examination Patent Publication (KOKAI) No. 57-18758 discloses addition of an organosilicon compound having a tetraorganoguanidyl group.
The compositions thus provided with a mildew-proofing property, however, are incapable of retaining the mildew-proofing property for a long time, because the mildew-proofing agent used will exude from the composition in the presence of water.